New insight into rectal function in pediatric defecation disorders: Disturbed rectal compliance is an essential mechanism in pediatric constipation

Objective To evaluate rectal sensitivity inpatients with pediatric constipation (PC) and nonretentive fecal soiling (FNRFS) using pressure-controlled distention (barostat). Study design Thresholds for rectal sensitivity (first sensation, urge to defecate, and pain), and rectal compliance were determined using a barostat. Results A total of 69 patients with PC (50 males; mean age, 10.9 +/- 2.2 years) and 19 patients with FNRFS (15 males; mean age, 10.0 +/- 1.9 years) were compared with 22 healthy volunteers (HVs) (11 males; mean age, 12.7 +/- 2.6 years). Sensitivity thresholds were not significantly different among the 3 groups. Rectal compliance was increased in 58% of the patients with PC (P < .0001 vs HVs). Rectal compliance did not differ between patients with FNRFS and HVs. Children with PC with abnormal rectal function required significantly larger rectal volumes at urge to defecate. Conclusions increased compliance is the most prominent feature in patients with PC. Because of higher compliance in these children, larger stool volumes are required to reach the intrarectal pressure of the urge to defecate. Children with FNRFS have normal rectal function.